Heat and cold insulation for M mud trap made of rigid polyurethane foam in the form of slate. The lagging has a cylindrical shape corresponding to the geometry of the insulated surface. Complete isolation is usually made of two half-shells with longitudinal and frontal locks, which, when folded, eliminate gaps, facilitate assembly and can be assembled and disassembled several times with tapes and clips. Price for products up to +150 C on individual request.